Two-speed transmission



Aug. 16, 1949. H.' F. WILMS 2,479,445

TWO- SPEED TRANSMIS S ION Filed-June 12, 1946 2 Sheeias-Sheet 2 FIG. 3

HENRY WILMS.

Patented Aug. 16, 1949 TWO-SPEED TRANSMISSION Henry F. Wilms, Cleveland,Ohio, assignor to The Elwell-Parker Electric Company, Cleveland, Ohio, acorporation of Ohio Application June 12, 1946, Serial No. 676,260

1 Claim.

The present invention relates to a two speed gear transmissionparticularly Suitable for use in electrically driven industrial trucks.

It is often desirable to provide a gear reduction in an electricallydriven industrial truck so that the truck may be driven by a directdrive for normal loads and through a gear reduction for abnormal loads.The present gear transmissions require a relatively lengthy period forchanging from one gear to another and during that time the motor isdisconnected from the drive wheels, and unless the operator turns thecurrent off, the motor will "speed up or run away," inasmuch as thesemotors are generally series wound. Thus, when approachinga grade, forexample, the truck operator must decide before he starts up the gradewhich gear speed to select, or otherwise, he may-be forced to stop onthe grade in order to change the gears.

An object of the present invention is to provide a two speed geartransmission for electrically driven industrial trucks in which the gearratios are changed with such rapidity that the motor cannot obtainexcessive speeds although the motor is maintained energized during thegear changing operation.

Another object of the invention is to provide a gear transmission forindustrial trucks in which the gears are always in mesh and the gearratios maybe changed without causing disengagement of certain gears andthe meshing of certain other gears.

Other objects and advantages of the invention willbe apparent from thefollowing description of a preferred form of the invention, referencebeing made to wherein:

Fig. 1 is a diagrammatic illustration of an industrial truck embodyingthe invention, part of the truck being broken away to show the locationof the transmission;

' Fig. 2 is a side viewof the gear transmission, a portion'of certainmembers of. the transmission being shown broken away and in section;.

Fig. 3 is a view in section of the gear transmission, the view beingtaken line 8-3, of Fig. .4;

Fig. 4 is a view in section taken substantially on line 4-4 of Fig. 3,but on a smaller scale; and

Fig. 5 is a fragmentary view in section taken along line 5-5 of Fig. 4.

Referring to the drawings, there is shown an industrial truck S-that isadapted to be driven the accompanying drawings by anelectrical rnotorindicated generally at 8,-

which motor is powered bys'uitable batteries substantially along,

carried on the truck, but which are not shown. The truck is providedwith driving wheels 1 which are driven by the motor 6 through a geartransmission 8 and a conventional axle, not shown. The truck is alsoprovided with dirigible wheels '9 and a load-carrying elevator or platform l0. There is provided the usual electrical controls for the motor 6as well as steering apparatus for the wheels 9, but since thesemechanisms are well known, they have been omitted from the drawings forthe sake of clarity.

The speed transmission 8 includes a casing formed by members l2 and I3,which members are secured together by bolts l4. Preferably, gaskets 15are interposed-between the abutting parts of the members l2 and I3forming an oiltight seal between the two members. The casing is providedwith an opening I9 through which lubricating oil may be introduced intothe casing, the opening being closable by a plug l8 threaded into theopening.

The member I2 is provided with a flange l6 by which the transmission maybe secured to the motor housing I! by bolts [8 extending throughopenings in the flange. The member I2 is also provided with a partitionwall having a central opening 2| through which a drive shaft 22 of themotor 6 is extended. A ball bearing 23 is secured in the opening 2| andthe drive shaft 22 is journalled in this bearing. Preferably, an oilseal 24, which may be of any well known type suitable for this purpose,is inter posed between the walls of the opening 2| and the shaft 22 forpreventing the loss of oil from the casing.

The casing member l3 has an opening 25 formed therein which is axiallyaligned with the opening 2| of casing member I2 and a flanged collar 26is press fitted in the opening and secured to the casing by a pluralityof bolts 21, only one of which appears in the drawing. A driven shaft28, which is connected with the axle of the truck through the usualsuitable mechanism, not shown, extends through the collar 26 and isjournalled in the collar by a ball bearing 29, which bearing is pressfitted in the collar 26. Preferably, a seal 29*,similar to seal 24, isprovided betweenshaft 28 and the inside of collar 26 for preventing lossof oil from the casing. The shafts 22 and 28 are axially aligned, andthe inner end of the driven shaft 28 is provided with a gear 30 which isformed integral therewith. Also, the inner end of shaft 28 is recessedand carries a ball bearing 3| in which a reduced end portion 32 of thedrive shaft 22 is journalled. Thus, the inner end of the drive shaft 22is further supported in the end of the driven shaft 28.

A drive gear 34 is secured to the end of the drive shaft 22 by a splinedconnection so that the gear is positively driven by the shaft, and thediameter of the gear 34 is somewhat less than the diameter of the gearon the driven shaft 28.

A cone clutch member 36, which includes a hub portion 31, is mounted onthe drive shaft 22 and is adapted to be rotated ,by, 2.2 through teeth38 which mesh with the teeth 40 of the gear 34. At the periphery-ofclutch member 35 is a flange portion 61,"which'f orms a clutchingsurface 42, the purpose of which wiii be made apparent hereinafter.Ereferably, a washer 43 is interposed between the bearing 23 and themember 35 for maintaining the latter in driving relation withxthe gear34.

A dnum-like housing 45 is provided which .is adapted to-rotate about anaxis common to that of the shafts .22 and .23. The housing 4-5 is formedby two dish shaped complementary mem hers 4,6 and 4 which are joinedtogether by a plurality jQif bolts :48. The housing member 41 isgotatively supported on a flanged sleeve 51) :by a ball bearing 5|having the outer race press fitted in the sleeve 5.0 and the inner racepress fitted on ,a head 52 formed on the ,driven shaft 2&1. .ireferably, a spacer washer .53 is provided between the bearings 29 and51..

fIhe housing 45 irotatabgl-y supports a vplurality of sets o-fqgears 5 4and 55, only one of which sets appears in the drawings, the gears ofeach set being interconnected so that each set of gears notateas a unit.These gears are both mounted on hafts 56 that are in turnjeurnalled inspanwa in t e members A$- nd-.4 P e e l h e are three sets 0f gears --54and 55, but .it is to be understood that any convenient number of setsof gears may-be used, and the sets are spaced apart equally forestablishing ,a balanced condition about the housing. Gear 55 is ofgreater diameter than gear 54 and gear 55 is in nesh at times with gear34 of the drive shaft 22 and gear 54 is mesh at all times with gearItilwof the driven shaft .23. Thus, it will "be apparent that the'housing 45 is rotated as :a unit'vvith the drive shaft 22, there willbe a direct drive established between the drive shaft and driven shaft.If the housing 454s maintained stationary yvh-ile the drive shaft 22 isdriven, there will be r a speed reduction between the drive shaft andthe driven shaft through gears and 55. In carrying out my invention I,provide .ineans for causing the housing 45 to rotate :as aun it withthe drive shaft for obtain;- mg adir'ect drive, and means is alsoprovided for maintaining the housing 445 stationary when it is .desiredto cause a gear reduction to be efI-ected.

11nbrdertoprovide for the control of the move mnt of housing .45, thehousing may be moved lhn'gitudirially of its axis in opposite directionsfrictional engagement with'two oppositely disposedelutch andbrakemembers 36 and 58,, respecten; In the present embodunent of theinvention onemember is fixed or non-rotative and serves as -a brake andthe other clutch men adapted to rotate. The outer p riphery of themember '45 of'ho'using 45 is tapered and this poiition is adapted/1 ofrictionally engage ,a commentary tapered tac 'elon the flange 41 of flg h c-n mb r an w he h u in is s moved to its left-hand position, as isshown in Fig. 3. The periphery of the member 41 of casing 45 is taperedand this portion is adapted to frictionally engage a complementarytapered surface 58 formed about the interior of the housing member I 3when the casing 45 is moved from the clutch member 36 to the right, asviewed in Fig. 3. Thus, when the casing 545 is moved into engagementwithlthe clutchmember 36; the casing 45 will be rotated with the drive shaft22 through the medium of the clutch member 36, and when ,the casing 45is moved to its righthand position, it is maintained stationary byengagement with the surface 58 of the casing,

which surface acts as a brake. It will be noted masonry a slightmovement of the casing along is necessary to cause engagement with cheerthe other o'f'the members 36 or 58 which controls the rotation of thecasing.

The casing is normally urged into frictional ensa n n wi h the t h membe13 by a n ur rl tv of to sprmss 60, l n .of

are as many springs 60 as thereare sets of gears 54 and 155.

For the purposes of moving the housing 45 its axis, the member 41 has :acollar portion 55 formed thereabout and ran outtu-rned flange 65 formedin the outer end of the neck-like portion.

t m n n u a h n abo th ut end of the casing 4-5 and two semi-cicrularshoe members .51 secured together by bolts H to form an annularoperating shoe, are mounted in the channel. The shoe members 5!! eachinclude a err r r t am er 5.8 w at i i e d t0 he shoes by rivets 69. Theshoe members are each o d wi a lat all e t ndin n by which the operatingshoe may be actuated.

Ifhe operatingshoe 6-1 is adapted-to be actuated in opposition tosprings 5 1) by a pair of ear-ms hi w ine b a ubu a o e 1.4 w i h yokeis' supported on a shaft 15 journalled bearings 15 formed .the housingmember 13. The yoke vimenaber 14 is keyed to the shaft 55 as indicatedat 11 so that when the shaft k5 is rotated, the arms 13 will rock in thedirection of "the'aires of the shafts 22 and 28. The lower ends .of thearms 13 receiye the pins IQ of the Sha '61 "5 h? memes vthe s a t 5 hshoe 5! will \cause'm vement of .th ehousinglfi along'its'aiiis.

The shaft 15 is adapted to he rocked a handleyer '80 ,or a foot pedal,8! both located conveniently to the .Qperatornf truck. The leverBfl'isjounnalled on the shaft 15 and it is provided with'aniarm 2. "'Ihearm 82 is .connected to a lever '83, which is pivoted at 54 to thecasing 3., by a link Q5, the link being con nested to the ,ends of {82and lever .83 by pivot connections. Lever-"83 lhas Za toggiehnk 8Epivotal'ly' connected thereto at 8?! land the toggle .link 85 extendsthrough an phoning eu hr u a e o bl in .8 th t journalled within a slot89 firmed in :the end of a l v gfl- The-e cs eend-g ev r sexed to theshaft 15 so that swinging of lever 90 rotates the shaft 15.

A relatively heavy coil spring 92 is interposed between the pin 88 and acollar 93 threaded on the toggle link 88 for establishing a resilientreaction between lever 90 and the toggle link 86. When the lever 80 isin the position shown in Fig. 1, which corresponds to the full lineposition shown in Fig. 2, the center of the joint 87 will lie above aline interconnecting the centerof pivot 84 and the center of connectionbetween link 86 and pin 88. Thus, the tension of spring 92 will tend tomaintain the lever 83 biased counterclockwise and against a stop 96provided on the casing 8. This maintains the housing 45 against theclutching surface 58 and the gear transmission will be in low gear. Whenlever 80 is moved clockwise as viewed in Fig. 1, the toggle betweenlever 83 and link 88 will be broken and lever 83 will be rotatedclockwise against stop 98 as shown by the dotted lines of Fig. 2 andlever 90 will be moved clockwise by the force of springs 60 actingthrough housing 45 arms 13 and shaft 15 to permit movement of thehousing 45 into engagement with the clutch member 36 for eifectingdirect drive between the driving and driven shafts.

If desired, the operator may shift the housing operating mechanism byuse of pedal 8|. Pedal 8| is pivoted on a bracket I88 by a pin I01, andthe rear end of the pedal 8| is connected to lever 83 by a link I02.

It will be apparent that by my invention, the operator of the truck mayquickly change the gear ratio of the truck without the necessity ofattending to the electric control of the motor and a smooth change ofgear ratios may be eflected at any time desired.

Although I have described but one form of embodiment of the invention,it is to be understood that other forms might be adopted, all

falling within the scope of lows.

I claim:

A two speed drive transmission for industrial the claim which foltrucksand the like, comprising, a drive shaft and a driven shaft axiallyaligned with one another and each having a gear mounted thereto; ahollow housing mounted for rotation about the axis of said shafts andfor axial movement relative to said shafts; two connected gearsjournalled in said housing, one of said connected gears being meshedwith the gear on the drive shaft and the other connected gear beinmeshed with the gear on the driven shaft; an annular clutch membermounted on the drive shaft and disposed adjacent to one side of thehousing; a brake member disposed adjacent the opposite side of thehousing, said clutch and brake members being alternately engaged by saidhousing when thehousing is moved in opposite directions axially forfrictionally connecting one or the other of said members with thehousing, said clutch member being rotated relative to the brake member;a support element mounted for rotation about the axis of said shafts andwithin said hollow housing; a spring interposed between said supportelement and a wall of the housing for urging the housing toward one ofsaid members; and means for moving the housing against the action ofsaid spring and into engagement with the other of said members.

HENRY F. WILMS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 802,175 Seeley Oct. 17, 1905924,323 Daimler June 8, 1909 958,797 Fentress May 2'4, 1910 1,167,718Rost Jan. 11, 1916 1,540,247 Bowman June 2, 1925 FOREIGN PATENTS NumberCountry Date 9,111 Great Britain Apr. 19, 1902, 128,940 Germany Mar. 17,1902

